DE102015120674A1 - GEAR FLUID HEATING SYSTEM AND GEAR FLUID HEATING METHOD - Google Patents

Abstract

A vehicle includes a transmission having gears lubricated by oil and a variable voltage converter (VVC). The VVC includes an inductive component arranged in such a way that the oil is in contact with the inductive component. In addition, the vehicle includes at least one controller configured to operate the VVC to deliver a desired power. The controller, in response to a temperature of the oil being lower than a threshold, changes a voltage and a current of the VVC while maintaining the desired power to increase heat dissipation through the inductive component.

Description

TECHNICAL AREA

 The present disclosure relates to a system and method for heating transmission fluid, and more particularly, heating the transmission fluid with an inductive power device.

BACKGROUND

 The term "electric vehicle" as used herein includes vehicles having an electric working machine for vehicle propulsion such as battery electric vehicles (BEV), hybrid electric vehicles (HEV) and plug-in hybrid electric vehicles (PHEV). A BEV includes an electrical work machine, wherein the power source for the electrical work machine is a battery that is rechargeable from an external power grid. In a BEV, the battery is the power source for vehicle propulsion. An HEV includes an internal combustion engine and one or more electric machines, wherein the power source for the engine is fuel and the power source for the electric machine is a battery. In an HEV, the engine is the main source of vehicle propulsion, with the battery providing additional energy for vehicle propulsion (the battery buffers fuel energy and recovers kinetic energy in electrical form). A PHEV is like an HEV, but the PHEV has a higher capacity battery that can be recharged from an external power grid. In a PHEV, the battery is the main source of vehicle propulsion power until the battery depletes to a low energy level, at which time the PHEV operates as an HEV for vehicle propulsion.

 Electric vehicles include a voltage converter (DC-DC converter) connected between the battery and the electric working machine. In addition, electric vehicles having AC electric working machines include a power converter connected between the DC-DC converter and each electric working machine. A voltage converter increases ("increases") or decreases ("decreases") the voltage potential to enable torque performance optimization. The DC-DC converter includes an inductive arrangement (or choke arrangement), switches and diodes. A typical inductive arrangement includes a conductive coil wound around a magnetic core. As current flows through the coil, the inductive assembly generates heat.

 Furthermore, electric vehicles include a transmission or transaxle. The transmission includes transmission fluid such as oil for lubricating gears and performing other transmission functions. The transmission works more efficiently when operating within a desired temperature range. By reducing the time it takes for the transmission to reach the desired temperature range, vehicle fuel economy is improved.

SUMMARY

 In accordance with one embodiment, a vehicle includes a transmission that has gears that are lubricated by oil. A variable voltage converter (VVC) includes an inductive component arranged to contact the oil with the inductive component. In addition, the vehicle includes at least one controller configured to operate the VVC to deliver a desired power. In response to a temperature of the oil being lower than a threshold, the controller changes a voltage and a current of the VVC while maintaining the desired power to increase heat dissipation through the inductive component.

 In accordance with another embodiment, a vehicle includes a transmission having gears that are lubricated by oil and a traction battery. A variable voltage converter (VVC) is electrically connected to the battery and includes an inductive component arranged to contact the oil with the inductive component. In addition, the vehicle includes at least one controller configured to receive a signal indicative of an oil temperature and to reverse a polarity of a battery current if the oil temperature is below a threshold for increasing the heat output by the inductive component.

 In accordance with yet another embodiment, a method for heating a transmission of a hybrid vehicle is disclosed. The vehicle includes a variable voltage converter (VVC) having an inductive component in contact with transmission oil. The method includes operating the VVC to dispense a desired power and, in response to a temperature of the oil being lower than a threshold, changing a voltage and current of the VVC while maintaining the desired power to control heat dissipation by the VVC to increase inductive component.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic diagram of a vehicle.

2 is a circuit of a variable voltage converter (VVC) off 1 ,

3 is a graph showing the viscosity of the transmission oil as a function of the temperature.

4 FIG. 4 is a front view of a transmission and a VVC having an inductive arrangement and illustrates a structure for supporting the inductive arrangement within the transmission. FIG.

5 is a schematic representation of a power electronics housing.

6 FIG. 3 is an enlarged front perspective view of an inductive assembly including a support structure in accordance with one or more embodiments.

7 is a sectional view of the inductive arrangement 6 along the section 7-7.

8th is an exploded view of the inductive arrangement 6 ,

9 FIG. 10 is a flowchart for increasing the temperature of the transmission oil in accordance with an embodiment. FIG.

10 FIG. 14 is a table showing voltage and current outputs of the VVC and the associated circuitry for various modes of operation.

11 FIG. 10 is a flowchart for increasing the temperature of the transmission oil in accordance with another embodiment. FIG.

12 FIG. 10 is a flowchart for increasing the temperature of the transmission oil in accordance with yet another embodiment.

13 FIG. 12 is a graph showing the operation of the inductor during a hypothetical drive cycle of the vehicle. FIG.

DETAILED DESCRIPTION

 Embodiments of the present disclosure are described herein. However, the disclosed embodiments are, of course, merely examples, and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Thus, specific structural and functional details disclosed herein are not to be construed as limiting, but merely as a representative basis for teaching those skilled in the art how to make various use of the present invention. As one of ordinary skill in the art understands, various features illustrated and described with respect to any of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of illustrated features provide representative embodiments for typical applications. However, for certain applications or implementations, various combinations and changes in the features may be desired in accordance with the teachings of the disclosure.

In 1 is a transmission 12 within a plug-in hybrid electric vehicle (PHEV) 16 shown that is an electric vehicle powered by an electric machine 18 with the assistance of an internal combustion engine 20 can be driven and that can be connected to an external power supply network. The electric machine 18 may be an AC electric motor that is in 1 as "engine" 18 is shown. The electric machine 18 receives electrical power and provides drive power for vehicle propulsion. In addition, the electrical machine works 18 as a generator to convert mechanical power through regenerative braking into electrical power.

The gear 12 can have a power split configuration. The gear 12 contains the first electric machine 18 and a second electric machine 24 , The second electric machine 24 may be an AC electric motor that is in 1 as a "generator" 24 is shown. The second electric machine 24 receives like the first electric machine 18 electrical power and provides an output torque. In addition, the second electric working machine acts 24 as a generator to convert mechanical power into electrical power and to power flow through the transmission 12 to optimize.

The gear 12 contains a planetary gear unit 26 a sun wheel 28 , a planet carrier 30 and a ring gear 32 contains. The sun wheel 28 is with an output shaft of the second electric machine 24 connected to receive a generator torque. The planet carrier 30 is with an output shaft of the engine 20 connected to receive an engine torque. The planetary gear unit 26 combines the generator torque and the engine torque and adjusts the ring gear 32 a combined output torque ready. The planetary gear unit 26 acts as a continuously variable transmission without any fixed gear ratios or "step" ratio ratios.

In addition, the transmission can 12 a one-way clutch (OWC) and a generator brake 33 contain. The OWC is connected to the output shaft of the engine 20 coupled to allow the output shaft to rotate in one direction. The OWC prevents the transmission 12 the engine 20 drives backwards. The generator brake 33 is with the output shaft of the second electric machine 24 coupled. The generator brake 33 can be activated to the output shaft of the second electric machine 24 and the sun wheel 28 to "brake" or prevent their rotation. Alternatively, the OWC and the generator brake 33 be omitted and through control strategies for the engine 20 and for the second electric machine 24 be replaced.

The gear 12 includes a countershaft, the idler gears including a first gear 34 , a second gear 36 and a third gear 38 having. A planetary gear 40 is with the ring gear 32 connected. The planetary gear 40 meshes with the first gear 34 to move between the planetary gear unit 26 and the countershaft to transmit a torque. An output gear 42 is with an output shaft of the first electric machine 18 connected. The output gear 42 meshes with the second gear 36 to switch between the first electric machine 18 and the countershaft to transmit a torque. A transmission output gear 44 is with a drive shaft 46 connected. The drive shaft 46 is about a differential 50 with a pair of driven wheels 48 coupled. The transmission output gear 44 meshes with the third gear 38 to move between the gears 12 and the driven wheels 48 to transmit a torque. In addition, the transmission includes a heat exchanger or an automatic transmission fluid cooler 49 for cooling the transmission fluid.

The vehicle 16 includes an energy storage device such as a battery 52 for storing electrical energy. The battery 52 is a high-voltage battery, the electrical power to operate the first electric machine 18 and the second electric machine 24 can deliver. In addition, the battery receives 52 electrical power from the first electric machine 18 and from the second electric machine 24 when they work as generators. The battery 52 is a battery pack consisting of several battery modules (not shown), each battery module containing a plurality of battery cells (not shown). Other embodiments of the vehicle 16 consider other types of energy storage devices, such as capacitors and fuel cells (not shown) that charge the battery 52 supplement or replace. A high voltage bus connects the battery 52 electrically with the first electric machine 18 and with the second electric machine 24 ,

The vehicle contains a battery energy control module (BECM) 54 to control the battery 52 , The BECM 54 receives an input indicating vehicle conditions and battery conditions such as battery temperature, battery voltage, and battery current. The BECM 54 calculates and estimates battery parameters such as battery level and battery performance. The BECM 54 provides indicative of a battery state of charge (Bsoc) and a battery performance for other vehicle systems and the vehicle controller output (Bsoc, P _cap).

The gear 12 contains a DC-DC converter or a variable voltage converter (VVC) 10 and a power converter 56 , The VVC 10 and the power converter 56 are electrically between the main battery 52 and the first electric machine 18 ; and between the battery 52 and the second electric machine 24 connected. The VVC 10 "increases" or increases the voltage potential of the battery 52 provided electrical power. In accordance with one or more embodiments, the VVC "reduces" or decreases 10 also the voltage potential of the battery 52 provided electrical power. The power converter 56 performs an alternating direction of the through the main battery 52 (via the VVC 10 ) supplied DC power to AC power to the electric machines 18 . 24 to operate. In addition, the power converter is aimed 56 by the electric machines 18 . 24 provided AC power in DC equal to the main battery 52 to load. Other embodiments of the transmission 12 include a plurality of power converters (not shown) such as each of the electric machines 18 . 24 assigned power converter. The VVC 10 contains an inductive arrangement 14 ,

The gear 12 contains a transmission control module (TCM) 58 for controlling the electrical machines 18 . 24 , the VVC 10 and the power converter 56 , The TCM 58 is configured, among other things, the position, the speed and the power consumption of the electric machines 18 . 24 to monitor. In addition, the TCM monitors 58 electrical parameters (eg, voltage and current) at various locations within the VVC 10 and the power converter 56 , The TCM 58 provides for other vehicle systems this information corresponding output signals.

The vehicle 16 contains a vehicle system controller (VSC) 60 which communicates with other vehicle systems and controllers to coordinate their function. Although shown as a single controller, the VSC 60 include a plurality of controllers that may be used to control multiple vehicle systems in accordance with overall vehicle control logic or overall vehicle control software.

The vehicle controller including the VSC 60 and the TCM 58 generally include any number of microprocessors, ASICs, ICs, memory (eg, FLASH, ROM, RAM, EPROM, and / or EEPROM) and software code to interact to perform a series of operations. In addition, the controllers contain predetermined data or "look-up tables" based on calculations and test data stored within the memory. The VSC 60 communicates with other vehicle systems and vehicle controllers (eg, the BECM) via one or more wired or wireless vehicle connections using a common bus protocol (eg, CAN and LIN) 54 and with the TCM 58 ). The VSC 60 receives an input (PRND) indicating a current position of the transmission 12 (eg, park, reverse, idle or drive). In addition, the VSC receives 60 an input (APP) representing an accelerator pedal position. The VSC 60 represents an output representing a desired wheel torque, a desired engine speed, and a generator brake command for the TCM 58 ; and a contactor control for the BECM 54 ready.

The vehicle 16 includes a brake system (not shown) that includes a brake pedal, a brake booster, a master cylinder, and mechanical links with the driven wheels 48 to effect the friction braking contains. In addition, the brake system includes position sensors, pressure sensors, or some combination thereof to provide information such as the brake pedal position (BPP) that corresponds to a driver demand for brake torque. In addition, the brake system includes a brake system control module (BSCM) 62 that with the VSC 60 communicates to coordinate regenerative braking and friction braking. The BSCM 62 can issue a regenerative braking command for the VSC 60 provide.

The vehicle 16 includes an engine control module (ECM) 64 to the engine 20 to control. In addition, the VSC 60 for the ECM 64 provides an output (the desired engine torque) based on a number of input signals including APP that corresponds to a driver request for vehicle propulsion.

The vehicle 16 can be configured as a plug-in hybrid electric vehicle (PHEV). The battery 52 receives via a charging port 66 periodically AC power from an external power supply or from an external power grid. In addition, the vehicle contains 16 an on-board charger 68 that the AC power from the charging port 66 receives. The charging device 68 is an AC / DC converter that converts the received AC power into DC power used to charge the battery 52 suitable is. The charging device 68 in turn performs the DC power while recharging the battery 52 to. Although the VVC 10 in the context of a PHEV 16 is shown and described, it can be implemented in other types of electric vehicles, such as in an HEV or in a BEV.

Based on 2 contains the VVC 10 a first switching unit 78 and a second switching unit 80 for increasing the input voltage (V _bat ) to provide an output voltage (V _dc ). The first switching unit 78 contains a first transistor 82 that becomes a first diode 84 is connected in parallel, but their polarities are reversed (antiparallel). The second switching unit 80 contains a second transistor 86 that turns into a second diode 88 is connected in anti-parallel. Every transistor 82 . 86 may be any type of controllable switch (eg, an insulated gate bipolar transistor (IGBT) or a field effect transistor (FET)). In addition, every transistor becomes 82 . 86 individually through the TCM 58 controlled. The inductive arrangement 14 is shown as an inductive input device between the traction battery 52 and the switching units 78 . 80 is connected in series. The inductive component 14 generates a magnetic flux when a current is supplied. When the over the inductive component 14 changes flowing current, a time-varying magnetic field is generated and a voltage is induced. When current passes through the inductive component, the inductive component generates 14 Warmth. Other embodiments of the VVC 10 contain other circuit configurations (eg, more than two switches).

The VSC 60 determines, in response to a driver torque request, the amount of power that the electric machines from the traction battery 52 must be supplied to the Meet torque requirement. The power is equal to V _dc × current. The system circuitry may change V _dc and the current to provide a same performance more efficiently. For example, V _dc can be decreased and the current can be increased. If the V _{dc is} equal to V _bat , no voltage will be induced and less heat loss will be experienced. This operation is known as a bypass mode and occurs when V _{dc is} equal to V _bat . The bypass mode may be ideal during low torque requests (such as during stationary speed and low acceleration travel), but is not ideal during a high torque request. During high torque demands, the V _dc required to supply sufficient power is higher than V _bat . The switches 78 . 80 operate the inductive component 14 to increase V _bat to the required V _dc . During normal driving cycles, the system regularly cycles into and out of bypass mode, causing the inductive component to generate waste heat. The waste heat can be used to heat the transmission oil.

One reason for the reduced transmission efficiency is increased friction losses due to the transmission oil 96 , The friction losses are a function of the viscosity of the oil. The more viscous the oil is, the higher the friction losses. The viscosity of the oil is a function of temperature. Generally speaking, colder oil is more viscous than warmer oil. Based on 3 FIG. 14 shows a hypothetical graph of transmission oil viscosity over a range of oil temperatures. FIG. As the temperature increases, the viscosity of the oil decreases until the oil reaches a threshold temperature. After the threshold temperature, the oil viscosity remains substantially constant over a range of elevated temperatures. The diagram may be divided into two zones, a heating zone in which the viscosity varies in accordance with the oil temperature, and an operating zone in which the viscosity is substantially constant. In order to increase the fuel efficiency of the vehicle, it is ideal to move from the warming zone to the operating zone as quickly as possible. The transmission generates heat and heats itself, but the transmission heating time can be reduced by adding external heat to the transmission fluid. The through the inductive component 14 Waste heat generated may be added to the transmission oil to reduce transmission heating time and to improve vehicle fuel economy.

In 4 is a front view of the gearbox 12 and the VVC 10 shown. The gear 12 contains a gearbox 90 , which is shown without cover to show internal components. As described above, the engine included 20 , the motor 18 and the generator 24 Output gears, with corresponding gears of the planetary gear unit 26 comb. These mechanical connections occur within an inner chamber 92 of the gearbox 90 on. The gear 12 contains a transmission fluid 96 such as oil for lubrication and cooling of the gears that are inside the gearbox 92 located (eg the intermediate gears 34 . 36 . 38 ). The transmission chamber 92 is sealed to the fluid 96 to contain. In addition, the transmission can 12 Valves, pumps and lines (not shown) contain the fluid 96 through the chamber 92 to circulate. To the fluid 96 Cool down, can be a heat exchanger or cooler 49 be used.

On an outer surface of the gearbox 12 is a power electronics housing 94 assembled. The power converter 56 and the TCM 58 are inside the power electronics housing 94 assembled. The VVC 10 is an arrangement with components inside and / or outside of a gearbox 12 can be mounted. The VVC 10 contains an inductive arrangement 14 , In this arrangement, there is the inductive arrangement 14 inside the gearbox 90 so that heat from the inductive component 14 to the gearbox 12 is transmitted. In addition, the VVC contains 10 a number of switches and diodes (in 2 shown) in the power electronics housing 94 are mounted outside the gearbox 12 is, and with the inductive arrangement 14 are functionally coupled. Because of the inductive arrangement 14 within the transmission 12 is mounted, is the exposed surface area of the inductive arrangement 14 with the transmission fluid 96 in direct contact. The gear 12 contains an additional structure to the inductive arrangement 14 to support while allowing the transmission fluid 96 flows over the structure to contact the exposed surface area.

Rotating elements (eg gears and shafts) can be fluid 96 shift to other components or "splash". Such a "spray" area is designated by the letter "A" and is located in an upper portion of the chamber 92 , If the inductive arrangement 14 is arranged in the area A, heats the inductive arrangement 14 the transmission fluid 96 generated by the rotating elements (eg from the second idler gear 36 and from the differential 50 ) splashes away as they turn.

The gear 12 can nozzles 98 included to transmission fluid 96 directly on components inside the case 90 to spray. Such a "spray" area is designated by the letter "B" and is located in an intermediate portion of the chamber 92 , The inductive arrangement 14 can be mounted inside the area B, so that transmission fluid 96 through the nozzle 98 on the inductive arrangement 14 is sprayed. The sprayed transmission fluid 96 is due to the inductive arrangement 14 heated while it is in contact with the inductive component. The inductive arrangement 14 can also gear fluid 96 received from nearby rotating elements (eg from the planetary gear unit 26 ) splashed away. Other embodiments of the transmission 12 consider several nozzles and nozzles in other locations of the chamber 92 are mounted (eg, a nozzle mounted in the area A).

Furthermore, the transmission fluid collects 96 within a lower section, which also acts as a reservoir or as a sump 99 the chamber 92 is known. Such a "dip" area is indicated by the letter "C" and is located in a lower section 99 the chamber 92 , The inductive arrangement 14 can be mounted within the area C and into the transmission fluid 96 be submerged. The inductive arrangement 14 heats the transmission fluid 96 ,

In 5 is a power electronics housing 94 shown in an alternative embodiment. In this embodiment, the VVC 10 , the power converter 56 , the TCM 58 and the inductive arrangement 109 all inside the case 94 arranged. The housing 94 contains a first opening 101 and a second opening 103 , An inlet fluid line 105 gets through the first opening 101 receives and provides fluid for the inductive assembly 109 ready. An outlet fluid line 107 is through the second opening 103 receive and provide a return for the fluid. The fluid is via the inductive arrangement 109 circulated to heat from the inductive arrangement 109 which causes the fluid to heat up. The inductive arrangement 109 is sealed to prevent fluid from the other electrical components within the housing 94 damaged. The inlet and outlet fluid lines 105 . 107 are connected to the gearbox installation.

The 6 to 8th illustrate the inductive arrangement 14 in accordance with one or more embodiments. The inductive assembly may be at various locations in the vehicle, such as within the transmission housing 90 be arranged. The inductive arrangement 14 contains a ladder 110 formed on two adjacent tubular coils, a core 112 and an insulator 114 , The inductive arrangement 14 contains the insulator 114 which is formed as a two-piece bracket and the conductor 110 and the core 112 supports. In addition, the isolator disconnects 114 the leader 110 physically from the core 112 and is formed of an electrically insulating polymer material such as polyphenylene sulfide (PPS).

The leader 110 is formed of a conductive material such as copper or aluminum and two adjacent helical coils, a first coil 111 and a second coil 113 , wrapped. The coils may be formed by using a rectangular (or flat) type of conductive wire by a portrait process. From the leader 110 Both input and output lines go out and connect to other components.

The core 112 may be formed in a double "C" configuration. The core 112 contains a first end 116 and a second end 118 each formed in a curved shape. In addition, the core contains 112 a first leg 120 and a second leg 122 to the first end 116 with the second end 118 to join together to form an annular core 112 to build. Every thigh 120 . 122 contains several core elements 124 spaced apart to define air gaps. The core 112 may be formed of a magnetic material such as an iron-silicon alloy powder. Between the core elements 124 can ceramic spacers 126 be arranged to maintain the air gaps. At the core 112 An adhesive may be applied to the position of the ends 116 . 118 and the thigh 120 . 122 including the core elements 124 and the spacer 126 maintain. As in 6 shown in dashed lines may alternatively be around an outer periphery of the core 112 a band 128 be attached to the position of the ends 116 . 118 and the thigh 120 . 122 maintain.

The insulator 114 can be considered as a bobbin structure with a first half section 130 and with a second half section 130 ' , which are generally symmetrical to each other, be formed. Every half section 130 . 130 ' contains a base plate 134 . 134 ' for fixing the arrangement 14 , The base plate 134 . 134 ' contains openings 136 . 136 ' for receiving fasteners (not shown) around the inductive assembly 14 to mount on a support structure such as a gearbox or other housing. From the base plate 134 . 134 ' goes across a stiffening 138 . 138 ' out. From the bracing 138 of the first half section 130 go a pair of bobbins including a first bobbin case 140 and a second spool box 142 out to make sure they have a corresponding first coil box 140 ' and with a corresponding second coil box 142 ' from the bracing 138 ' of the second half section 130 ' go out, are engaged. In one embodiment, the first bins are 140 . 140 ' Coaxially aligned along a first longitudinal axis (not shown) and are the second bobbins 142 . 142 ' along a second longitudinal axis (not shown) parallel to the first longitudinal axis, coaxially aligned. The bins 140 . 140 ' . 142 . 142 ' are each formed in a tubular shape with a generally square-shaped cross-section.

The insulator 114 protects the conductor 110 and the core 112 , The first bins 140 . 140 ' are engaged with each other to share an exterior surface 144 for supporting the first coil 111 provide. In addition, the first bins define 140 . 140 ' a cavity 146 for picking up the first leg 120 of the core 112 , Similar are the second bobbins 142 . 142 ' engaged together to form an outer surface together 148 for supporting the second coil 113 to provide a cavity 150 for picking up the second leg 122 of the core 112 define. In accordance with the illustrated embodiment, the bins include 140 . 140 ' . 142 . 142 ' several holes 152 to heat transfer from the thighs 120 . 122 to facilitate by allowing the fluid 96 easy through the bins 140 . 140 ' . 142 . 142 ' goes. Other embodiments of the insulator 114 contain unbalanced half sections (not shown). For example, the bins may extend from one of the half sections and are received by the stiffener of the other half section (not shown).

The VSC 60 can the VCC 10 operate in a less efficient mode, the more heat from the inductive component 14 generated to increase the heating rate of the transmission oil. This mode may be referred to as a heat generation mode. In 9 is a control logic 200 to operate the VVC 10 in a heat generation mode to accelerate the heating of the transmission fluid. The control logic 200 is implemented using software code that resides within one or more of the controllers, such as the VSC 60 , the TCM 58 and / or the ECM 64 is included. In the operation 202 the controller determines the temperature of the transmission oil. The transmission oil temperature can be determined directly with a sensor or can be inferred using other measurements and data.

In the operation 204 the transmission oil temperature is compared to a transmission oil temperature threshold to determine if the transmission oil temperature is lower than the threshold temperature. If the transmission oil temperature is higher than the threshold temperature, the controller goes to operation 212 over and becomes the VVC 10 operated normally, since the transmission does not use the additional heating. If the transmission oil is below the threshold temperature, the controller determines in the operation 206 whether the shaft speed of the gears within the transmission is high enough to produce a splash. If the shaft speed is too low, the controller goes to operation 212 above. If the shaft speed is sufficient, the controller goes to the operation 208 above. In some embodiments, the operation may 206 be omitted.

If the driver power request is within a threshold range, the VVC may 10 working in the heat generation mode. If the power demand is out of the threshold range, the heat generation mode is impossible. For example, the VVC 10 normally operated to provide the driver requested torque if the driver torque request is too high. In the operation 208 the controller determines if the current power request is within the threshold range. If this is not the case, the controller goes to the operation 212 above. If it does, the controller goes to operation 210 above.

In the operation 210 becomes the switching operation of the VVC 10 changed to more heat from the inductive component 14 to create. In normal operation, the controller selects a V _dc value that is as close as possible to V _bat for any given driver power request. If the transmission heating is desired, the controller may change the switching operation to increase V _dc to increase heat in the inductive component 14 to create.

10 shows possible V _dc values and current values that can be used to meet a 20 kilowatt driver power requirement. In this example, V _bat 200 volts. The V _dc and current values can be changed by changing the operating speed of the switches. In order to generate more current via the inductive component and thus to generate more heat with the inductive component, the switching speed can be increased.

Alternative A shows an efficient operating condition that produces less heat in the inductor. In alternative A, V _{dc is} equal to V _bat and the VVC is working 10 in bypass mode. If it is desired to heat the transmission oil, the operation of the VVC 10 be changed to generate more heat in the inductive component. In alternative C, the switching speed is increased to allow more current through the inductive component 14 to send. The alternative C is a less efficient operating condition and generates more heat within the inductor 14 , In alternative C, they are supplied with 20 kilowatts of power, but _{Vdc is} 400 volts and the current is 50 amps. The V _bat has been increased by 200 V to a V _dc 400 volts provide. The inductive component 14 is used to increase the voltage, which generates heat.

The 11 to 13 provide another method for increasing the heat output of the inductive component 14 In this method, the battery cells are cycled through to heat dissipation of the inductive component 14 to increase. Based on 11 the schedule starts at the operation 300 by determining the temperature of the transmission oil. The transmission oil can be measured with a transmission oil sensor or can be inferred about other measurements. In the operation 302 the controller determines if the transmission oil is cold. The oil is cold if the battery temperature is below a temperature threshold. The temperature threshold may be a predetermined constant based on transmission specifications programmed in the memory of the controller. If the oil temperature is below the temperature threshold, additional heating is desired to improve vehicle performance. If the oil temperature is not below the threshold, additional efforts to increase the oil temperature are unnecessary.

In the operation 304 the controller determines whether the driver power demand is in a range suitable for alternative VVC operation. For example, the VVC 10 operated normally to supply the necessary power to the vehicle driveline to meet the driver demand, if the driver torque request is high. If the driver torque demand is in a range suitable for alternative VVC operation, the controller determines in the operation 306 whether the shaft speed is high enough to produce syringes. If the shaft speed is too low to produce syringes, the controller goes to operation 308 over and becomes the VVC 10 operated normally. In some embodiments, the operation is 306 omitted. For example, the operation is 306 omitted if the inductive component 14 directly sprayed by oil.

If the shaft speed is high enough, the controller goes to operation 310 above. In the operation 310 the controller determines if a "one-touch" event has occurred. A single-touch event indicates that the driver is demanding extra power or vehicle acceleration. A one-touch event may be indicated by detecting that the accelerator pedal is being pressed rapidly. If a typing event has occurred, then 312 the battery voltage is assessed to determine if sufficient battery voltage is available to provide the additional required power. If the battery voltage is low, no additional power is provided and the process returns to operation 300 back. If the battery voltage is not low, the polarity of the battery current in the operation 314 vice versa (polarity here refers to charging or discharging), which reduces the polarization resistance voltage and heats the inductive component.

Similarly, the controller determines at 316 whether a "strobe" event has occurred. A strobe event indicates that the driver requires less power or vehicle deceleration. A stroking event may be indicated by braking the vehicle, lifting the foot off the accelerator pedal, or a combination of braking and / or lifting the foot off the accelerator pedal. If a Austipp event has occurred, then 318 the battery voltage is assessed to determine if the energy can be charged with energy recovered by regenerative braking or by another energy recovery system. If the voltage is high, no extra energy can be stored by the battery and the process returns to operation 300 back. If the battery voltage is not too high, will be in the operation 314 the polarity of the battery is reversed, thereby increasing the heating rate of the inductor.

If there are no typing or skipping events, the controller evaluates 320 continue, whether the terminal voltage of the battery has reached a limit. The limit is based on the polarization resistance voltage. If the terminal voltage is at the limit, in the operation 314 the polarity of the battery is reversed to temporarily make the polarization resistance voltage zero and increase the heating rate of the inductive component. If the terminal voltage is not at the limit, the process returns to operation 300 back.

In 12 a flowchart of an alternative embodiment is shown. In the operation 321 the schedule begins by determining the temperature of the transmission oil. In the operation 322 the controller determines if the transmission oil is cold. The oil is cold if the battery temperature is below a temperature threshold. If the oil temperature is below the temperature threshold, additional heating is desired to improve vehicle efficiency. If the oil temperature is not below the threshold, additional efforts to increase the oil temperature are unnecessary and become the VVC 10 operated normally.

In the operation 324 the controller determines if a typing event has occurred. If at 324 a one-tap event occurs and the battery voltage at 326 is not low, the polarity of the Battery included 328 reversed quickly or with a high slew rate. Likewise, the polarity is added 328 also quickly reversed, if at 330 a one-tap event occurs and the battery voltage at 332 not too high. However, the polarity in the operation 336 vice versa with a low slew rate if the terminal voltage is at 334 is on the limit. Optionally, additional polarity reversal ramp rates can be used. For example, for a one-tap event, a first slew rate may be used, a second slew rate may be used for a strobe event, and a third slew rate may be used for a clamp voltage event. Alternatively, any combination of equal or unequal slew rates could be used for each event type.

 A high slew rate produces more heat in the inductor than a lower slew rate, but is more detectable by the driver. However, because the polarity reversal process allows higher slew rates during a single tap or a strobe event, higher ambient noise levels mask noise. In addition, the driver may expect the engine to increase or decrease speed during a tap-in or skip event. For example, more power is required from the battery and the engine, which causes the engine to work harder and increase the noise level within the vehicle when a tap-in event occurs. If no polarity reversal is expected or initiated by the driver, a lower slew rate may be used. For example, a lower slew rate is used when a clamp voltage limit is reached because the increased ambient noise levels that accompany engine acceleration or engine deceleration are absent. The low slew rate reduces the perceptibility of any change in engine speed or noise that may result from the terminal voltage limit polarization reversal. Consequently, several slew rates help treat the noise sensitivities of the occupants.

In 13 is a graph showing how the schedules of the 11 and 12 related to the power requirements of the battery. In the graph, the horizontal axis represents time, and the vertical axis represents the battery power target level. In the area above the power zero line, the battery is discharged and charged in the area below the power zero line. The horizontal lines labeled "Limit" indicate the physical charge and discharge limit of the battery.

 Starting at point A and progressing from left to right, the battery is charged between points A and B. At point B, the terminal voltage reaches the polarization resistance voltage limit and the battery can not accept additional charge without first reversing the battery polarity. From points B and C, the battery current is reversed at a low rate of increase. If the zero line is crossed, separating the charging and discharging areas, the polarity reverses.

 From point C to D the battery is discharged. At point D, the polarization resistance voltage limit of the battery is reached and the polarity must be reversed again. From point D to E, the battery slew polarity is reversed with a low slew rate.

 From point E to point F the battery is charged. At point F, the polarization resistance voltage threshold is reached. From point F to point G, the battery slew polarity is reversed at a low slew rate. Between points G and H, the battery discharges. At point H, a strobe event occurs. Between points H and I, battery high polarity is reversed at a high rate of rise.

 From point I to point J, the battery is charged. At point J, the polarization resistance voltage threshold is reached. While the polarity between points J and K is reversed, another strobe event occurs. At point K, the battery current has already changed direction (i.e., point K is on the opposite side of the zero line from point J), which means that the polarity resistance voltage has been overcome. Consequently, polarization reversal back to the charge region is allowed.

 From point L to point M the battery is charged. At point M, the polarization resistance voltage threshold is reached, and from point M to point N, the polarity is reversed. From point N to point O, the battery is discharged. At point O, the battery voltage threshold is reached, and between points O and P, the battery slew polarity is reversed at a low slew rate.

 From point P to point Q, the battery is charged. At point Q, a one-tap event occurs. From point Q to point R, the battery slew polarity is reversed at a high slew rate.

 From point R to point S, the battery is discharged. At point S, the polarization resistance voltage is satisfied. From point S to point T, the polarity is reversed. While the polarity is reversed, a tap-in event occurs at point T. Since the point T has a polarity other than the point S, a polarity reversal for discharging is allowed and the polarity is reversed to point U with a high slew rate.

 From point U to point V, the battery is discharged. At point V, another one-tap event occurs. A new discharge performance target is calculated and set at point W. From point W to point X, the battery continues to discharge. At point X the polarization voltage threshold is reached and at point Y the polarity is reversed at a low slew rate.

 From point Y to Z, the battery is charged. At point Z, a typing event occurs. A new discharge power target level AA is calculated and set at a high slew rate. From point AA to point BB, the battery is discharged. At point BB, another typing event occurs. A new discharge power target CC is calculated and set at a high rate of increase. The process of reversing polarity and setting power target levels will continue based on changes in battery status and driver inputs.

 Although exemplary embodiments have been described above, these embodiments are not intended to describe all possible forms encompassed by the claims. The terms used in the specification are words of description rather than limitation, and of course various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments may be combined to form other embodiments of the disclosure that may not be explicitly described or illustrated. Although various embodiments may have been described as having or may benefit from other embodiments or implementations of the prior art with respect to one or more desired properties, one of ordinary skill in the art will recognize that one or more features or features are included to achieve desired overall system attributes that depend on the specific application and implementation. These attributes may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, ease of use, weight, manufacturability, ease of assembly, and so forth. Thus, embodiments described as being less desirable in relation to one or more characteristics than other embodiments or prior art implementations are not outside the scope of the disclosure and may be desirable for particular applications.

Claims (20)

 A vehicle comprising: a gearbox containing gears that are lubricated by oil; a variable voltage converter (VVC) including an inductive component arranged in such a manner that the oil is in contact with the inductive component; and at least one controller configured to operate the VVC to dispense a desired power and to change a voltage and a current of the VVC in response to the temperature of the oil being lower than a threshold while maintaining the desired performance to increase the heat output by the inductive component.  The vehicle of claim 1, wherein the transmission further includes a housing and wherein the inductive component is mounted within the housing.  The vehicle of claim 2, wherein the transmission further includes nozzles to spray the oil directly onto the inductor.  Vehicle according to one of claims 1 to 3, further comprising: a power electronics housing attached to the transmission, the inductor being mounted within the power electronics housing; and Fluid conduits connected to the inductor and configured to circulate oil between the inductor and the transmission.  The vehicle of any one of claims 1 to 4, wherein the controller is further configured to increase the voltage and proportionally decrease the current in response to a temperature of the oil being lower than a threshold while maintaining the desired performance. to increase the heat output through the inductive component. The vehicle of any one of claims 1 to 5, further comprising a transmission shaft coupled to at least one of the gears, and wherein the controller is further configured to receive a signal indicative of a rotational speed of the shaft and the VVC in response that the speed is higher than a threshold speed, for Increase the heat output to operate through the inductive component.  The vehicle of claim 1, wherein the controller is further configured to receive a signal indicative of a driver torque request and to operate the VVC in response thereto to increase heat dissipation through the inductive component if the driver torque request is below a threshold lies.  A vehicle comprising: a gearbox containing gears that are lubricated by oil; a battery; a variable voltage transformer electrically connected to the battery and including an inductive device arranged to contact the oil; and at least one controller configured to receive a signal indicative of an oil temperature and to reverse a polarity of a battery current if the oil temperature is below a threshold to increase the heat output by the inductive component to heat the oil.  The vehicle of claim 8, wherein the controller is further configured to reverse the polarity of the battery current if the oil temperature is below the threshold and if a single tap event, a strobe event or a terminal voltage event has occurred.  The vehicle of claim 8, wherein the controller is further configured to reverse the polarity of the battery current if the oil temperature is below the threshold and if a tap-in event or a roll-out event has occurred.  The vehicle of claim 10, wherein the controller is further configured to reverse the polarity of the battery at a first ramp rate for the one-tap event and to reverse at a second ramp rate for the skip event.  The vehicle of claim 11, wherein the first rate of increase is higher than the second rate of increase.  The vehicle of claim 8, wherein the inductive component is mounted within the transmission.  The vehicle of claim 13, wherein the transmission further includes nozzles to spray the oil directly onto the inductor.  A method of heating a transmission of a hybrid vehicle, the vehicle including a variable voltage converter (VVC) having an inductive device in contact with transmission oil, the method comprising: Operating the VVC to dispense a desired power and in response to a temperature of the oil being lower than a threshold, changing a voltage and a current of the VVC while maintaining the desired power to increase heat dissipation through the inductive component.  The method of claim 15, wherein the inductive component is mounted within the transmission.  The method of claim 16, further comprising injecting the oil onto the inductive component by rotating gears within the transmission.  The method of claim 16, further comprising injecting oil directly onto the inductor with a nozzle.  The method of any one of claims 15 to 18, further comprising increasing the voltage and reducing the current proportionally while maintaining the desired power to increase the heat output by the inductor if the temperature of the oil is lower than the threshold. includes.  The method of claim 15, further comprising receiving a signal indicative of a transmission shaft speed, and wherein the operation is commenced in response to the shaft speed being above a threshold speed.

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